0:00
I'm Jerry Sebag,
professor of clinical optomology
at the Doheny Eye Institute
and founding director
of the VMR Institute
for Vitreous Macula
Retina in Southern California.
We'll now consider the visual impact
of a posterior vitreous detachment
that is not anomalous in part 2.
0:24
The last topic that I'm
going to be discussing
is a consequence of posterior
vitreous detachment that
has previously been
considered an innocuous event
but is currently being
reconsidered in terms of a disease.
Recall that posterior vitreous
detachment requires liquefaction
of the gel, vitreous, as well as
dehiscence at the vitreo-retinal
interface in order for the
poster vitreous detachment
to be innocuous.
And by innocuous, what
we're referring to
is that there are none of the
anomalous changes that we've just
considered that result
in retinal tears
and detachments, vitreo-macular
traction syndrome,
macular holes, and macular pucker.
In the absence of all of those
manifestations of anomalous PVD,
it has previously been considered
that a PVD is innocuous.
However many patients
experience floaters.
And in some of those individuals,
the floaters are serious.
1:26
The origin of the floaters
is light scattering
by the dense collagen matrix of
the posterior vitreous cortex.
Recall that I mentioned
earlier, the reason
we can visualize the peripheral
vitreous by dark field slit
microscopy is because
there's a very dense
aggregation or a high
density of collagen
fibrils in the peripheral vitreous.
And that's shown here on
scanning electron microscopy.
It is a bit exaggerated
by the dehydration
that the specimens have to undergo
in order for the preparation
for scanning EM, but
I think it's very
useful for demonstrative purposes,
to appreciate what that looks like.
And here you can see the appearance
of the posterior vitreous cortex
in preset lens
biomicroscopy in an eye.
This is the optic disk here.
The retinal vessels are
branching from the optic disk,
and this is the location
and the typical appearance
of posterior vitreous detachment.
